Formation of an image on various substrates can be accomplished in a wide variety of ways. Relatively recently, interest and research has increased in the area of thermosensitive color-changing or color-forming materials, including inks and coating materials. These thermosensitive color-changing materials can be used in a myriad of applications which benefit from an undeveloped state being either colorless or having a particular color and a developed state having a distinctly different color appearance. Transformation from the undeveloped state to the developed state is most often via a chemical reaction between a leuco dye and a suitable activator or reducing agent that can be present in the color-changing material(s). Commercially useful thermosensitive color-changing materials can have a somewhat limited color palette; however, research efforts continue to focus on improving available color choices and properties such as light stability, fade resistance, intensity, and the like.
One recent development includes the use of infrared absorbers in conjunction with leuco dyes. The infrared absorbers can be specifically selected to produce heat under exposure to electromagnetic radiation at a given frequency, or range of frequencies. The heat then provides the necessary energy for the leuco dye to be developed. In this way, precise control can be used to selectively develop portions of the leuco dye to form an image. One example of this technology is the LightScribe (trademark of Hewlett-Packard Company) CD and DVD marking system.
In accordance with this general technology, materials and methods that further enhance the above image forming technologies and improve commercially useful image properties continue to be sought through research and development.